Old gas sediment in old tank

J

jimh6278

Petty Officer 3rd Class
Joined
Aug 21, 2006
Messages
75
I just removed the top unit from an old OMC pressure tank with 40 year old gas in it. My local mechanic took the gas off my hands but the tank has a skim of brown crud on the bottom. This crud has also plugged up the screen on the pickup tube and is up the walls of the tank about an inch. The tank itself is in great shape and when I use a stick on the inside to scrape the crud the paint looks new.

My question is - what is a good solvent to use to get rid of the crud film and clean the tank (now that benzene is not available to us.). Advice would be appreciated.

Jim
 
rolmops

rolmops

Vice Admiral
Joined
Feb 24, 2002
Messages
5,517
Re: Old gas sediment in old tank

You can also fill up the tank with 85% ethanol or even paint thinner.It will dissolve the varnish that is left in the tank.
Then take a hand full of roofing nails,add them to whatever you have chosen to clean the tank with and do some serious shaking.That usually does a wondrous job at cleaning out the crud.
 
G

GeneH

Petty Officer 2nd Class
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Sep 1, 2007
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Re: Old gas sediment in old tank

I think by paint thinner the above poster means lacquer thinner not enamal reducer. Sometimes it works but give it soak time.
 
asdasc

asdasc

Senior Chief Petty Officer
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Aug 28, 2008
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Re: Old gas sediment in old tank

How would dumping some carb cleaner in there work? Isn't it designed to clean out gummed up old gas? I am thinking of the stuff that comes in the gallon can for soaking carb bodies. Let it set about 20-30 minutes and slosh it occasionally. Keep checking on it and don't let it set too long. Rinse when done with water.
 
R

Rick.

Captain
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Jul 30, 2006
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3,740
Re: Old gas sediment in old tank

I would try the varsol/paint thinner first and if that doesn't do it then carb. cleaner. You haven't said anything about rust so I will presume there is no rust present, just crud. Make sure you remove the pick-up and screen and clean it separately. It won't take the abuse of nails etc. running over it. You can plug the hole with a pipe plug. I cleaned rust from mine using an electrolisis method and I was pretty happy with the result but it took a great deal of time and effort. If you have a bunch of rust then I would probably get the tank liner stuff that T.D. suggested. Rick.
 
J

jimh6278

Petty Officer 3rd Class
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Re: Old gas sediment in old tank

The paint thinner didn't work. I did a little experiment with the pickup tube that was really crudded up. I mixed 2/3 Super Clean and 1/3 hot water and put the mixture in a mason jar. I then stuck the pickup tube in and let it soak for an hour. It seemed to work. The crud was gone from the tube and the screen is clear. However, I still can?t get water to flow thru the tube. I read somewhere that there is a check valve of some type in the tube but my service manual doesn?t show it. I think it was Max Wawryzyniak in his cheap Outboard Book that said poke a hole in the screen with an awl to release the check valve. I tried air at 40 psi and nothing happened. It appears that the pick-up tube is a single unit and the screen holder is pressed on. I can?t get it off. I assume there is a check valve but what is it and how do I break it loose. i can use 150 psi air but that might tear up the screen.

As far as my tank goes it is a warm day and it is sitting out with a gallon of Super Clean and in a couple hours I am going to take it to a car wash and see how that works.
 
J

jimh6278

Petty Officer 3rd Class
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Aug 21, 2006
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Re: Old gas sediment in old tank

Boy - did that ever work. The Super Clean softened all the old sediment and the high pressure wash followed by 2 high pressure rinses left the tank shiny bright. Absolutely clean and I didn't even spray myself.

Would still appreciate an answer on the pick-up check valve if anybody knows what it looks like. Maybe rubber?
 
T

tmcalavy

Rear Admiral
Joined
Aug 29, 2001
Messages
4,005
Re: Old gas sediment in old tank

Drop the pick-up valve/mechanism into a parts cleaner and leave it for a week or three. Plain old alcohol will help dry out the tank, if it still needs it. You may be able to pick up a new/used valve at the free classifieds at www.aomci.org
 
J

jimh6278

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75
Re: Old gas sediment in old tank

Ok, I'm back with 2 issues.

1. The check valve in the pickup is still not free. If i knew what the valve actually was i could figure out how to deal with it. Has anybody taken one apart. Is it a rubber flapper, ball bearing in a slot, etc. What exactly is it.

2. I am having trouble finding the diaphragm for the tank. The one I removed looks exactly like the one pictured in the 1956 service bulletin. When I ordered the part by part number the one i received is different, one large and one small hole. The parts people have looked and they cannot find one that looks like mine. If some one can tell me how to post jpg pictures of the old, new, & service bulletin I can show my problem.
 
E

ezeke

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Sep 19, 2003
Messages
12,532
Re: Old gas sediment in old tank

I'm not sure which of the check valves you are looking for, but click the thumbnail and see if that diagram helps.
 

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J

jimh6278

Petty Officer 3rd Class
Joined
Aug 21, 2006
Messages
75
Re: Old gas sediment in old tank

That's it. First i'm going to try 150 pound air from the bottom. If that doesn't work I'm going to poke a wire down from the top and try to break it loose. It must be held on the sides. Last resort is to go thru the screen.

And the diaphragm part number in the service manual is 302563.
 
J

jimh6278

Petty Officer 3rd Class
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Aug 21, 2006
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75
Re: Old gas sediment in old tank

Ops. That is for the plunger. The check valve that is stuck is in the pickup tube. I've soaked it for a week with no success.
 
F

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: Old gas sediment in old tank

I believe the check valve is a flat metal disc. Go through the screen and poke it loose.

There are diaphragms for tanks with a metal primer button and a different one for tanks with a plastic button. They are available from Evinrude dealers or www.laingsoutboard.com
 
J

jimh6278

Petty Officer 3rd Class
Joined
Aug 21, 2006
Messages
75
Re: Old gas sediment in old tank

That is how I got the wrong diaphragms in the first place. I went to an online parts supply place, told them my tanks (I have 3) are all metal plungers, and the original part number is 302563, and I got the wrong part. If I knew what the sierra part number was I think I could get one.
 
J

jimh6278

Petty Officer 3rd Class
Joined
Aug 21, 2006
Messages
75
Re: Old gas sediment in old tank

I was able to send pictures to Laing and they sell the same thing I have. The guy told me to cut the additional hole with a razor blade - not my first choice.

I am thinking that there was a change sometime and OMC probably issued a service bulletin but I can't locate it. The cut sheet printed in "Cheap Outboards" is the one I have. I sent pics to Marine Engine which sells just the diaphragm but I have not heard back.

I have 3 of these tanks and would like to rebuild and sell them to help fund my old outboard habit.
 
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